The present invention relates to a device for locking an electric tool with a rechargeable battery pack.
In the field of mains-independent electric tools, such as hand-guided drills, drilling hammers and the like, increasingly more powerful machines with increasingly longer operating times are being developed. As a result, increasingly heavier rechargeable battery packs are required to provide the desired amount of energy. As the weight of the rechargeable battery pack increases, however, so does the potential for danger, e.g., if the rechargeable battery pack unexpectedly detaches from the housing of the electric tool—due to wear, contamination, material failure or the like—and falls downward. This could result in a fatal accident if it would occur at a high level.
To prevent unintended detachment of a rechargeable battery pack from a mains-independent electric tool, it is already known—with regard for large, heavy devices, in particular—to provide a “double lock” between the electric tool and the rechargeable battery pack. A double lock of this type is created using a device of the type described initially, which is composed of one or, typically, a plurality of locking bars supported in the housing of the electric tool such that, when the rechargeable battery pack is inserted, they are movable against spring force, and each of which is engaged via spring force in two lock-in grooves located in the rechargeable battery pack in series in the direction of insertion. When the locking bar engages in the first lock-in groove—located in the front, in the direction of insertion—the rechargeable battery pack is secured only relative to the housing, although an electrical connection between connecting contacts of the rechargeable current accumulator of the rechargeable battery pack and an electric circuit of the load of the electric device is not established until the locking bar engages in the second lock-in groove, which is second in position in the direction of insertion.
Although this can prevent the rechargeable battery pack from detaching unexpectedly from the electric tool if the locking bar does not engage properly in the rear lock-in groove if it is contaminated, if the spring breaks due to material weakness, or if the lock becomes tight or is completely blocked due to dirt, grease or any other foreign objects that entered the locking-bar recess, a double lock of this type cannot reliably prevent the rechargeable battery pack from falling even if a plurality of locking bars is provided for reasons of redundancy.